(i) X-Mitosis. Y-Meiosis (ii) (a) In X, there is no association of homologous chromosomes but in Y, homologouschromosomes pair up together to form bivalents during prophase-I.(b) In X, there is no crossing over as there is no formation of chiasmata but in Y, crossing over occurs at the chiasmata whereby some genes are swapped between homologous chromosomes.